Spark plug shield



` J. J. MAscucH 2,080,827

SPARK PLUG SHI ELD Original Filed July 1l, 1931 Patented May 18,l 1937 r UNITED STATES Y aoscxzv PATENT OFFICE N srnnx rino snrELn o I Joseph J. Mascuch,.Newark, N. J.

originar application July` 11, 1931, sensi No. 550,076..` Divided and this application Febru aryrz, 193s, sensi No, 657,156 o u i) Claims.

ing, all of the parts of theignitionsystem through which highyfrequency currentsfpass andgrounding the said conducting casing, itis possible to dissipate the energy of the electrical radiations directly to ground, thereby preventing the aforesaid interference. Itis an object of this invention Atoprovide a conductive casing or shielding for `the spark plugs `of internal combustion engines, wherebyinterferenceto radio communication equipment installed in proximity to the en-` gine willbe eliminated. 3 .o 1

This invention is applicable to all types of combustion engines and particularly to engines on unitssuch `as aeroplanes, motors boats, automoblies. submarineaetc. l

It is also desirable toprevent: outside electrical o impulses` from affectingthespark plugs. There- `fore,anotherobject of the invention is to provide a shield for a spark plug which will intercept and ground any electrical impulses coming from the outside.

Where; exposed spark plugs are used they are subject to breakdowns by reason of the eiect of oil,

o water, gasoline,` or the accumulation ofioreign o matter. Where the spark plugs are used on aero-` planes a breakdown or short in the plug will cause serious damage. Therefore, another object of the invention is tc provide ashield to surround a spark plug which will prevent water, gasoline or other p foreign substances from reaching .the plug.

40; Where the spark plugsfarelused on aircraft engins at high altitudes or under other conditions of low atmospheric pressure, at which time `the conduction of the surrounding air isi very much greaterthan theconduction of the compressed gas between the gap of the spark plug points,`there `is danger of the ignition `current flashing over or sparking toa nearby grounded conductor and .nat-

" ural sparking outlet at spark plug points; It is standard practice to maintaina distance oi.'` at 5o least %ths,of`an inch between any uninsulated conductor `carrying ignition current l from any grounded part. In providing "a shielding' means for the spark plug, it wouldbe necessary tojuse a o large and bulky grounded conductor to enclose the v A sparkplu unless other insulating means is pro-` ,i i ,o (Cl.` 1231-169) This invention relates to` spark plug shields and vided. `It is therefore a further specic object of this invention to provide a shielding means of moderate size for thespark plug which will provide a distance" of atleast %ths oi aninch be-Y tweenall uninsulated parts carrying high tension 5 ignition currentfrorn surrounding grounded parts. Changes of temperature will cause condensation i of moisture on the insulating body'of the spark plugs and snow, water or ice `which `may leak` through the shielding means and gather on 4the jo insulated body ofi the` sparkl `plug `will cause a short circuit and make it extremely diilicult Ato k start the engine without flrstwiping olif` all moisture fromthe insulated body of the sparkplug `and sparkplug leads. It is therefore a `further 15 speciiic object of this invention to provide a waterproof and `airtight shielding means for the spark plugs. Furthermore, by providing a `moistureproofshield the `air spaces' inside maybefilled with a suitable, semi-solid dielectric such aspetrfellm jelly to increase. the insulating qugnties zo ofthe shield. L i o l A further object of the invention islto provide a container for a spark plug which may be adapted to receive various types of unshielded spark plugs.

The invention consists of the construction, com- 25 bination and arrangement oi parts as herein illusti-ated, describedand claime i i In the accompanying drawing, forming part hereof, is `illustrated one form of embodiment of the invention, `in which drawing similar refer- 30 ,encer characters designate corresponding parts, `.and in which; 'f

` Figure l isl a verticalrsectiontaken approidmately on line I-l of Figure 2 looking in` theidi` rection indicated bythe arrowspand, l 35 Figure 2 is afront elevation, partly broken` away, of a spark plug shield. ,o

, The current` isfs'upplied from` the distributors `through conductors 39o encased in insulation 40.

The conductors are carried in shielded conduits 40 4l provided on their ends with ferrules 50 having shoulders 52 in contact with the spark plug shield o so that a continuous groundedcircuit is formed around the spark plugs and conductors. l

`The spark plug shield is designated generally 45 as 69 and comprises an open-bottomed cup 'In `to surround the `spark plug 68. The cup` 10 may be made longer or shorter to accommodate various types o f unshielded plugs 6B. 'Ihe cup lll is provided with an inwardly tapered 4bottom por- 50 tion 'H` so thatit-may beeasilyseatedon the cylinder head of the engine. The tapered portion 1| terminates in an inturned annular ilange 12. The flange 'l2y is adapted to abut the lower i skirt of the plug il. A copper washer Il may 56 t be secured inside the cup 18 above the flange 12 so as to insure sealing contact of the plug 68 with the cylinder head of the engine. 'I'he cup 18 is made sufficiently large to allowl a socket wrench to be used to screw thev plug 68 rmly is formed by bending the metal of the cup 19 Y Before the end 16` outward and downward. of the cup 18 is turned inward as shownin Figure 1, an annular L-shaped band oftsteel or other metal 11 is p-laced in the housing formed o by bendingjthe cup 10 and the end .16 is then bent inward to hold'the ring 11 in place.r `With this construction a rm foundation'is provided for the shoulder with the use of theleast o possible material so as to reduce the Weight.

Disposed over the cup 10 is a cap ,18 formed or molded of dielectric material such as bakelite. The cap 18 is electro-platedv or otherwise coveredwith metallic foil or other conductive means `19 to protectthecap 18`andalso to serve as an lelectrical conductor.

Onhthe lower end of the ycap 18 is formed `an annular depending flange 80 with 'ao recessn'i adjacent thereto.` A

special compound washer 82 is disposed in the i recess 8| so that-when the cap 18 is disposed `on'thecup 18 the ange 14 on Vthe lcup 10, will tact/with' the shoulder 15 on vthe cup 10.

,proof seal. rAt the same time the depending ilange 8D on-the cap 1.8 will bein electrical con- Aireinforcing member` 83` is disposed in the top of the molded cap 18. i v l l On one side of the cap 18 is disposed a screwlthreaded bushing 84 the inner face of which is `beveled as shown at 85 tov receive the `tapered face of a conical washer 54. The portion of the cap 18 `adjacent the conical washer .541 isialso beveledso thatthe washer 54 `will makeA a seal- `ing contact against the cap 18 andthe bushing 84. A collar nut 42 isused to hold the conduit 4| to the bushing 84. t

Through the center: of the bushing 84 "and throughthe cap `18 is an opening 86 to accom-v modate the conductor `39r with the insulation 40.

The opening 86 is madeat an angle tothe spark l `plug 68 so thatl the conductor V39 'and conduit `4|` will not be bent between the outlet 33.0171 the .manifold 25 *and the spark plug 68. The conductor 39 is usually madeof strand wire and the `ends of the ystrands of the conductor 39 are formed into one piece by solder 81, for the purpose hereinafter shown. l

Set in the` moldedlcap '18' immediately above the spark plug 68 islan `interiorly screw-threaded bushing :88. A screw 89 is disposed through the bushing` andv is .provided with a sharp point 90. 'I'hepoint 90 "of,l the" screw 89 is adapted to be forced through the insulation 40 and make contact with the conductor 39. The ends of the conductor 39 being held together by the solder l 81 the point 90 will spread thestrands of wire as i it is forced through 'and will `insure a good electrical contact.

Carried by the lower end of the screw89 is a coil spring 9|.` The upper end of the coil spring `9| may be soldered to the screw 89 and the lower end of the spring 9i `is adapted `.tomake contact `adjacent the wall of the cup 10.

' some means such` as the skirts described are used to prevent them. With the spark plug shielding means here( described it has been found very successful to fill the spaces in the cup 80, designated generally as 98, with a petroleum jelly or The cap 18 islheld onto the cup'19 by means of a spring bail 94 the ends of thebail 94 being disposed through the shoulder`15-and the ring 11.` .In screwing the spark plug 68 into position the cup `1l]` will be. turned around and the bail 94 will not alwaysfbein proper position to hold A down the cap 18. Therefore, a series of openings 95 are providedso that the bail 94 may be placed in any desired position. f` The ring 11 acts as a bearing for the bail 94 fand prevents the distortion of the openings 95 by: the bail 94; VAt the top `of the bail 94 is provided `a ball 96 which is freeto rotate on :the bail 94. When the cap 18 is placed on .the cup 10 the spring 9i is compressed and 4exerts tension against theocap 18.`

The'ball 96 is provided on the bail 94 so that the bail 94 may be easily swung to the'top of` the cap 18 and seated ina recess 91 provided therefor. With the construction the bail 94 will at al1 times hold the cap 18 iirinly on the cup 1D but will allow the cap 18 to be quickly removed `at.

. member` disposed withinsaid shoulder, a cap to seat on said shoulder and means carried by 'said shoulder to maintain the'cap on the cup.

2. A spark plugshield kcomprising a `cup to enclosea spark plug; said `cup having a shoulder formed on the upper edge thereof, a reinforcing member disposedwithin said shoulder, afcap` to seat on said shoulder and means pivoted in said shoulder to maintain the capon the cup.

' 3. A spark plug shield comprising a cup to enclose a spark plug, said V,cuphaving a shoulder` formed on the upper edge thereof, aj reinforcing 'v member disposed within said shoulder,` a cap vto seat on said 4shoulderand abail carried by said shoulder'andprovidedV with a rotatable member to seat on said cap to hold the cap on the cup...

"4.1 A spark plug shield comprising a cup to en-` close a spark plug,V said cup having a shoulder formed on the upper edge thereof, a reinforcing member disposed within said shoulder, a cap to seat on said shoulder, said shoulder and reinforcingmember being Yprovided with a plurality of openings and aretaining member to be selectivelydisposed in some `of said openings to maintain the `cap in position on the cup.

5. In a spark plug radio shield, a shielding cap and projecting into said bore to contact the ignition conductor, said cap being formed with a relatively short dielectric skirt to surround the contact means and a relatively long dielectric skirt to surround the upper portion of a spark plug and a metallic sheath on the outside of the dielectric body.

6. In a radio shield for spark plugs, a shielding cap adapted to be positioned over a spark plugcomprising a metal shell, a body of dielectric material within the shell, said body having 4a lateral opening to receive a conductor and said body being formed with a circular recess in alignment with the upper end of a spark plug, and a partially resilient contact means carried by the dielectric body and seated in said recess, said contact means being adapted to project into the lateral-opening to contact a conductor.

7. In a radio shield for spark plugs, a shielding cap adapted to be positioned over a spark plug comprising a metal shell, a body of dielectric material within the shell, said body having a lateral opening to receive a conductor and contact means carried by the body, the lower edge of said metal shell terminating in a depending flange adapted to make electrical contact with a complementary element of the radio shield and said lower edge of the shell being formed with an annular recess to receive a liquidproong packing, )u

8. A spark plug radio shield comprising, in combination, a cup to surround a spark plug, the upper end of said cup terminating in an annular iiange with a seat adjacent thereto, a cap to cover said cup comprising a metallic shell, a dielectric body in said shell, said shell and body being formed with an opening to receive a conductor, contact means carried by the dielectric body, the lower edge of said shell having a depending flange adapted to seat on the cup in electrioal contact therewith, the annular flange on the cup being adapted to enter an annular recess on the cap adjacent the depending ilange to make a liquidproof connection between the cup and the cap and means to hold the cap on the cup.

9. A spark plug radio shield comprising, in combination, a cup to surround a spark plug and a cap to cover the cup, said cap comprising a dielectric body, a metallic covering and contact means and a bail carried by the cup to removably hold the cap on the cup, the top of said cap being formed with a detent to receive the bail and having a reinforcing means carried in said dielectric body adjacent the detent.

JQSEPH J. MASCUCH. 

